#include <cmath>
#include <cstdio>
#include <cstring>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int n, i, h[27], max_h = -1;
    char word[12];
    for(i = 0; i < 26; ++i)
        scanf("%d", &h[i]);
    scanf(" %s", word);
    for(i = 0; i < strlen(word); ++i)
        if(h[word[i] - 97] > max_h)
            max_h = h[word[i] - 97];
    printf("%d\n", (int) strlen(word) * max_h);
    return 0;
}